Branched polycarbonate production method

Abstract

Provided is a method of producing a branched polycarbonate, including: a step (a) of subjecting an alkali aqueous solution of a dihydric phenol, phosgene, and a branching agent to a phosgenation reaction in the presence of an organic solvent to provide a reaction liquid; a step (b) of adding the alkali aqueous solution of the dihydric phenol and a polymerization catalyst to the reaction liquid obtained from the step (a) to provide a reaction liquid containing a polycarbonate oligomer; a step (c) of separating the reaction liquid containing the polycarbonate oligomer obtained in the step (b) into an organic solvent phase containing the polycarbonate oligomer and an aqueous phase; and a step (d) of causing the organic solvent phase containing the polycarbonate oligomer separated in the step (c) and the alkali aqueous solution of the dihydric phenol to react with each other to provide a reaction liquid containing the branched polycarbonate, in which a ratio (x/y) of an addition amount of the polymerization catalyst to be added in the step (b), which is represented by x mol/hr, to a chloroformate group amount of the polycarbonate oligomer in the reaction liquid obtained from the step (b), which is represented by y mol/hr, is 0.0035 or more.

The invention claimed is: 
     
       1. A method of producing a branched polycarbonate, comprising:
 a step (a) of subjecting an alkali aqueous solution of a dihydric phenol, phosgene, and a branching agent to a phosgenation reaction in the presence of an organic solvent to provide a reaction liquid; 
 a step (b) of adding the alkali aqueous solution of the dihydric phenol and a polymerization catalyst to the reaction liquid obtained from the step (a) to provide a reaction liquid containing a polycarbonate oligomer; 
 a step (c) of separating the reaction liquid containing the polycarbonate oligomer obtained in the step (b) into an organic solvent phase containing the polycarbonate oligomer and an aqueous phase; and 
 a step (d) of causing the organic solvent phase containing the polycarbonate oligomer separated in the step (c) and the alkali aqueous solution of the dihydric phenol to react with each other to provide a reaction liquid containing the branched polycarbonate, 
 wherein a ratio (x/y) of an addition amount of the polymerization catalyst to be added in the step (b), which is represented by x mol/hr, to a chloroformate group amount of the polycarbonate oligomer in the reaction liquid obtained from the step (b), which is represented by y mol/hr, is 0.0035 or more. 
 
     
     
       2. The method of producing a branched polycarbonate according to  claim 1 , wherein the polycarbonate oligomer has a weight-average molecular weight of 5,000 or less. 
     
     
       3. The method of producing a branched polycarbonate according to  claim 1 , wherein the branching agent comprises a compound represented by the following general formula (I): 
       
         
           
           
               
               
           
         
         wherein R represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R 1  to R 6  each represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogen atom. 
       
     
     
       4. The method of producing a branched polycarbonate according to  claim 3 , wherein the compound represented by the general formula (I) comprises 1,1,1-tris(4-hydroxyphenyl)ethane. 
     
     
       5. The method of producing a branched polycarbonate according to  claim 1 , wherein the dihydric phenol comprises a compound represented by the following general formula (1): 
       
         
           
           
               
               
           
         
         wherein R 11  and R 12  each independently represent a halogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, Z represents a single bond, an alkylene group having 1 to 8 carbon atoms, an alkylidene group having 2 to 8 carbon atoms, a cycloalkylene group having 5 to 15 carbon atoms, a cycloalkylidene group having 5 to 15 carbon atoms, a fluorenediyl group, an arylalkylene group having 7 to 15 carbon atoms, an arylalkylidene group having 7 to 15 carbon atoms, —S—, —SO—, —SO 2 —, —O—, or —CO—, and a and b each independently represent an integer of from 0 to 4. 
       
     
     
       6. The method of producing a branched polycarbonate according to  claim 5 , wherein the compound represented by the general formula (1) comprises 2,2-bis(4-hydroxyphenyl)propane. 
     
     
       7. The method of producing a branched polycarbonate according to  claim 1 , further comprising adding a terminal stopper to the reaction liquid obtained from the step (a). 
     
     
       8. The method of producing a branched polycarbonate according to  claim 1 , further comprising a step (e) of separating the reaction liquid containing the branched polycarbonate obtained in the step (d) into an organic solvent phase containing the branched polycarbonate and an aqueous phase containing an unreacted dihydric phenol. 
     
     
       9. The method of producing a branched polycarbonate according to  claim 8 , wherein at least part of the aqueous phase containing the unreacted dihydric phenol separated in the step (e) is used as the alkali aqueous solution of the dihydric phenol to be added in the step (b). 
     
     
       10. The method of producing a branched polycarbonate according to  claim 1 , wherein the chloroformate group amount of the polycarbonate oligomer in the reaction liquid obtained from the step (b) is defined as a molar amount per unit time of the organic solvent phase containing the polycarbonate oligomer separated in the step (c). 
     
     
       11. The method of producing a branched polycarbonate according to  claim 1 , wherein the polymerization catalyst comprises triethylamine.